School of Biological Sciences, University of Wollongong, Wollongong NSW, Australia.
Royal Botanic Gardens & Domain Trust, Sydney NSW, Australia.
PLoS One. 2018 Apr 11;13(4):e0194484. doi: 10.1371/journal.pone.0194484. eCollection 2018.
Foraging decisions tend to drive individuals toward maximising energetic gains within a patchy environment. This study aims to determine the extent to which rainfall, and associated changes in food availability, can explain foraging decisions within a patchy urbanised landscape, using the Australian white ibis as a model species. Ibis density, food consumption rates and food abundance (both natural and anthropogenic) were recorded during dry and wet weather within urban parks in Sydney, Australia. Rainfall influenced ibis density in these urban parks. Of the four parks assessed, the site with the highest level of anthropogenic food and the lowest abundance of natural food (earthworms), irrespective of weather, was observed to have three times the density of ibis. Rainfall significantly increased the rate of earthworm consumption as well as their relative availability in all sites. Overall, these density and consumption measures indicate that anthropogenic derived foods, mainly from direct feeding by people, explain the apparent distribution of ibis across urban parks. However, there was evidence of prey-switching when the availability of natural foods increased following rainfall, perhaps reflecting selection of particular nutrients.
觅食决策往往促使个体在斑块状环境中最大限度地获取能量。本研究旨在以澳大利亚白鹮为模型物种，确定降雨及其引起的食物可获得性变化在斑块状城市化景观中对觅食决策的影响程度。在澳大利亚悉尼的城市公园中，干旱和湿润天气期间记录了鹮的密度、食物消耗率和食物丰度（自然和人为）。降雨影响了这些城市公园中的鹮密度。在所评估的四个公园中，无论天气如何，拥有最高人为食物水平和最低自然食物（蚯蚓）丰度的公园的鹮密度是其他公园的三倍。降雨显著增加了所有地点的蚯蚓消耗率及其相对可获得性。总的来说，这些密度和消耗措施表明，人为衍生的食物（主要来自人类的直接投喂）解释了鹮在城市公园中的明显分布。然而，当降雨后自然食物的可获得性增加时，存在猎物转换的证据，这可能反映了对特定营养物质的选择。
